1 Fundamentals of Phytotherapy – Collaboration between universities, the dietary supplement and herbal industry, and the pharmaceutical industry is essential to promote the success of this research. In North America, government funding of human studies on the efficacy and safety of herbal preparations is just beginning. – Comparable to research on chemically defined drugs, research on herbal preparations is also carried out using molecular biological, pharmacological, and clinical techniques of investigation. – The findings of herbal research are published in recognized medical journals such as JAMA, the British Medical Journal, and Arzneimittelforschung. – Researchers are developing high-quality standardized extracts with proven efficacy. – Both basic research and clinical studies have repeatedly shown that whole-drug complexes are superior with respect to range of action and tolerability to isolated chemical constituents. 1. Results of physicochemical, biological and microbiological tests and a description of the testing methods (analytical testing, assessment of pharmaceutical quality) 2. Results of pharmacological and toxicological tests (assessment of drug efficacy and safety) 3. Results of clinical studies (efficacy and safety) – If the beneficial and adverse effects, and the side effects of a preparation are already known, empirical evidence acquired by scientific methods can be submitted instead of items 2 and 3. – Until 1994, the Commission E, a diverse group of scientists, physicians, pharmacists, physiatrists, biostatisticians, and representatives of the pharmaceutical industry was charged with the task of preparing monographs on the various medicinal plants. In this capacity, the Commission issued summaries and assessments of the published data on the pharmacology, toxicology, and clinical efficacy of 360 herbal medical preparations. These monographs are available in English, published by the American Botanical Council (see list of references, p. 479). – This valuable and influential effort should not be overrated however. The monographs are not referenced with the primary literature, and so cannot be peer-reviewed or critically evaluated, especially since, recognizing the explosion of recent scientific work, they have not been revised in nearly 10 years. – The German Cooperative on Phytopharmaceuticals (Kooperation Phytopharmaka) took over responsibility for revising the existing monographs in Germany in 1994. The revised monographs included a comprehensive review of the recent literature. Some of them are available in English. – In 1994 also the ESCOP (European Scientific Cooperative on Phytotherapy) was constituted in order to actualize the monographs on an European base (see list of references, p. 479) – This valuable and influential effort should not be overrated however. The monographs are not referenced with the primary literature, and so cannot be peer-reviewed or critically evaluated, especially since, recognizing the explosion of recent scientific work, they have not been revised in nearly 10 years. – According to the simplified reauthorization procedure for traditional medicines, traditional medicines must be labeled as follows: Traditionally used (a) as a roborant (strengthening agent) in…; (b) for improvement of general feeling in…; (c) to enhance organ function…; (d) to prevent XYZ…; or (e) as a mildly effective medical drug in case of.… Specific diseases must not be mentioned as indications for the traditional preparation. – Half of all medicinal plants on the market and two-thirds of all plant species are harvested from the wild. – For economic reasons, wild harvested herbs are preferably used in the cases of certain slow-growing plants and of plants of which there is a naturally abundant supply. – Cultivated herbs are used when the natural supply is not sufficient to meet demand or if a herb required for medicinal purposes is a protected plant species, such as purple coneflower, Echinacea purpurea, and goldenseal, Hydrastis canadensis. – Advantages of controlled farming • Uniform seed material, optimal growing conditions and harvesting times • Reduced risk of mistaken identity or adulteration • Reduction of impurities, microbial contamination, and residues from pesticides and heavy metals (especially in plants imported from developing countries) – Organic farming: Ensures the maintenance of natural growing conditions and is environmentally friendly. – Mainly used to enrich and optimize the primary constituents of medicinal plants. A way of standardizing active constituent levels. – Reduces the number and quantity of undesirable substances in the plants. – Enhances the resistance of the plants to atmospheric influences, diseases, and pests. – Homogeneity is achieved by optimization and wide-scale standardization of growing conditions (e. g., in cultures), and asexual propagation – Manufacturers use exact specifications for analyzing parent substances—meaning the herbs and their parts used—and herbal extracts made from them, using solvents such as ethanol. Specifications for assaying the content of target or primary constituents are just as exact and are designed to ensure that the chemical composition of the herbal extracts remains consistent from batch to batch. – Standardization ensures that the quality of medicinal plants and extracts made from them are reproducible and consistent. – Minimum concentrations of active principles in raw (unprocessed) herbs are specified in sources such as the German and European Pharmacopeias and, lately, the US Pharmacopeia. – Good harvesting practice takes into account the growth phase (time of year) and best time of day to harvest a given plant. – The drying process should be performed at a suitable temperature, without overheating, and under appropriate lighting conditions. – The plant material should be cut, cleaned, and stored without direct light exposure at an appropriate temperature in accordance with the rules of good professional practice. Herbal preparations such as liquids, capsules, or tablets should be stored away from heat and direct sunlight, preferably in glass containers that exclude oxygen. – In Germany, herbal medicinal preparations are subject to essentially the same standards for toxicity, teratogenicity, and mutagenicity/carcinogenicity as chemically defined drugs. End user suppliers and storage specifications are described below. – The processed plant material must be tested for a wide variety of different pesticides. In North America, manufacturers of herbal products must follow good manufacturing practices based on regulations for food products regarding cleanliness and safety. The Food and Drug Administration (FDA) does not currently require manufacturers to test herbal medicines that are generally recognized as safe (GRAS) and have been used in food products before 1 January 1958 for toxicity in the same way as pharmaceutical drugs, since manufacturers are allowed to make only minimal “structure– function” claims for herbal preparations. – Store in a cool (not cold), dark place, out of the reach of children. – Discard after the expiration date. – Factors that can reduce the shelf life of herbal medicines: • Exposure to air (keep in airtight bottles) • Humidity • Heat • Light (leading to oxidation-related decomposition) • Fungal or bacterial contamination (leading to formation of poisonous metabolites) • Evaporation – In order to identify plants that are spoiled or infested, the plant material should be inspected for mold, altered or unpleasant odor, insects, and traces of insects (cobwebs, etc.). – The pharmacist should be able to furnish information on the shelf life of herbal medicines (e. g., teas and other herbal remedies prepared in the pharmacy). – Herbal preparations should be stored in containers that are airtight, waterproof, lightproof, and fragrance-free. – Storage temperature: 10–20° C (50–68 °F).
1.1 Characteristics and Status of Herbal Medicines
Preliminary Remarks
Herbal medicine is a scientifically recognized complementary and alternative treatment method with proven efficacy.
In North America, herbal remedies are considered dietary supplements by law and are considered safe unless proven otherwise. Manufacturing standards are not as stringent as required for pharmaceutical drugs. While only a few “structure and function” claims (such as “benefits digestion”) can be made by manufacturers, many work around that limitation by making extensive use of “third-party” advertising in magazines and through company representatives.
In Germany, herbal remedies are defined as medicinal products by German Drug Law.
German legislators regard herbs and herbal remedies as medicinal products with specific pharmaceutical characteristics. Together with homeopathic and anthroposophic medicines, herbal medicines are classified as drugs of a special system of therapeutics.
According to German law, every physician must be knowledgeable about herbal medicine. North American physicians are not required to have this training, and few classes are offered in herbs or natural medicine in medical school.
The public interest in alternative therapies for general health maintenance and supportive treatment of chronic diseases has increased tremendously.
Distinctions Between the Different Types of Therapeutic Preparations
Herbal products: One of the main distinguishing features of herbal preparations is their complex chemical composition.
Chemical or synthetic drugs: Chemically defined drugs in general contain precisely definable quantities of usually one particular active ingredient and also accompanying substances.
Homeopathic remedies: Homeopathic products are prepared according to special formulation techniques and are prescribed according to the principles introduced by Samuel Hahnemann in the early nineteenth century. His “Law of Similars” states that the remedy prescribed, in a more or less highly diluted form, to cure a given condition or disease should be a substance that induces similar symptoms in healthy individuals when given in much higher amounts.
Anthroposophic remedies: Anthroposophic remedies are prepared according to the ideas and teachings of Rudolf Steiner.
Definitions
Herbal medicine: A time-honored system of healing practiced in every culture in the world. Science has modernized the system using analytical and pharmaceutical testing. The science-based practice of herbal medicine is now called phytomedicine or phytotherapy, which is a system of therapeutics in which diseases and disorders are treated with medicinal plants and preparations made from them using scientific principles.
Medicinal herbs: Medicinal products whose active ingredients consist exclusively of medicinal plants and preparations made from them. Using modern chemical and pharmaceutical methods, a number of popular herbal remedies are nowadays “standardized” to provide consistent levels of proven identified active compounds.
Pharmaceutical biology: The field of research concerned with the extraction and development of biogenic drugs from plants and other living organisms as well as the processing and application of these drugs.
Phytopharmacology: The study of the uptake, distribution, and effect of herbal preparations and of their elimination from the body.
Active principles: Substances or substance groups definable by chemical analysis that essentially contribute to the therapeutic action of a medicinal herbal preparation.
Active ingredients of medicinal herbal preparations: Plant ingredients in their natural states and preparations made from them.
Minor constituents: Substances that have an indirect or slight effect on the therapeutic action of an herbal drug.
Single-herb herbal preparation: Herbal medicinal preparation from one medicinal plant.
Target constituents: Herbal drug preparation constituents definable by chemical analysis that are used as parameters of in-process quality control and may contribute to a characteristic pharmaceutical property.
Species, genus, family: Taxonomic terms classifying a plant. A genus may include one or more species, and a family may include one or more genera.
Research on Herbal Remedies: State of the Art
Remarkable advances in phytotherapeutic research have been made within the past 15 years.
The worldwide interest in herbal drug research is steadily increasing.
German Drug Law Provisions
Phytopharmaceutical standards: In Germany, manufacturers of herbal preparations are held to much higher standards than their counterparts in North America. According to the German Drug Law (Arzneimittelgesetz), herbal “drugs” (preparations) must meet the same standards as chemically defined drugs with respect to pharmaceutical quality, efficacy, and safety, whereas in the United States they are considered dietary supplements.
1.2 From the Plant to the Remedy
Origins of Medicinal Plants for the Manufacture of Herbal Products
Wild harvested herbs
Cultivated herbs
Cultivation of special crops
Quality Assurance
Homogeneous starting materials
The concentrations of constituents in a given plant (e. g., ginseng or arnica) tend to vary according to location of origin, season of harvesting, and age.
Standardized preparation process
Chemical standardization: Many manufacturers today sell products that contain standardized extract powders in capsule and tablet form, and the levels of identified active constituents vary much less in these products.
Quality is ensured through good harvesting, drying, processing, and storage practices of both herbs and preparations (see also section on storage):
In-process controls: The manufacturer should monitor each step of the process of converting raw materials into finished medicinal products by applying the appropriate analytical tests.
Drug safety for herbal medicinal preparations
Plants collected in the wild, as well as plants raised in conventional (nonorganic) farms, may have high concentrations of pesticides and/or heavy metals.
End user suppliers: Pharmacies, supermarkets, health food stores, web-based suppliers, or by direct order from certain suppliers.
Storage
Plants infested with pests or mold must be destroyed.
Comparison of Efficacy
It is virtually impossible to compare the efficacy of herbal remedies prepared by different manufacturers, even when they are derived from the same plant species, because different companies use different drying, processing, and manufacturing processes, and because plants from different populations vary in constituent levels.
The therapeutic efficacy of herbal remedies with comparable concentrations of primary constituents but produced by different manufacturers may vary because of the differences in the content of minor constituents.
In the future, individual pharmaceutical companies will be required to test the efficacy and tolerability of plant extracts prepared by different manufacturing processes.
1.3 Constituents and Active Principles
Primary and Secondary Metabolism
A distinction is generally made between primary and secondary plant metabolism. The products of primary metabolism maintain the plant’s vital functions, whereas the products of secondary metabolism, as far as is currently known, are not essential for the plant’s immediate survival.
Products of primary metabolism:
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Phytochemistry: The study of plant chemistry, including the identification, isolation, analysis, and characterization of plant constituents, and determination of the chemical structures of plant constituents.
Marketing authorizations for herbal medical drugs: In Germany, applications for marketing authorization must be submitted to the Federal Institute for Drugs and Medicinal Products, accompanied by the following documents:
Insofar as the manufacturers of phytomedicines use different methods of processing, the final products may vary greatly with respect to the type and/or concentration of their ingredients. This is especially true of liquid tinctures of all kinds, including glycerites, and herb products that contain powdered herbs.
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